Correlate the clinical presentations of the following patients, who are experiencing ovula… — USMLE Step 2 CK

Correlate the clinical presentations of the following patients, who are experiencing ovulatory dysfunction and infertility, with their expected serologic hormone profiles.

A $22$ -year-old collegiate gymnast with a body mass index of $16.8 \text{ kg/m}^2$ experiencing secondary amenorrhea for $8$ months.Normal to low follicle-stimulating hormone (FSH), decreased luteinizing hormone (LH), low estradiol, and normal prolactin.
A $33$ -year-old woman with a history of vitiligo and hypothyroidism complaining of vaginal dryness, dyspareunia, and absent menses for the past $1$ year.Elevated follicle-stimulating hormone (FSH) and luteinizing hormone (LH), with low estradiol.
A $26$ -year-old woman with a body mass index of $34 \text{ kg/m}^2$ presenting with a $2$ -year history of unpredictable menses and coarse facial hair growth.Normal follicle-stimulating hormone (FSH), elevated luteinizing hormone (LH), normal estradiol, and elevated serum testosterone.
A $30$ -year-old woman with chronic headaches, secondary amenorrhea, and non-puerperal bilateral galactorrhea.Suppressed follicle-stimulating hormone (FSH) and luteinizing hormone (LH), very low estradiol, and hyperprolactinemia.

Answer

The gymnast pairs with low LH/FSH and low estradiol (Functional Hypothalamic Amenorrhea). The patient with autoimmune history pairs with elevated FSH/LH and low estradiol (Primary Ovarian Insufficiency). The obese patient with hirsutism pairs with elevated LH, normal FSH, and elevated testosterone (Polycystic Ovary Syndrome). The patient with galactorrhea pairs with high prolactin and suppressed FSH/LH (Prolactinoma).

Each etiology of amenorrhea disrupts the hypothalamic-pituitary-ovarian axis at a unique point. Functional hypothalamic amenorrhea is central and suppresses GnRH (low FSH/LH, low estrogen). Primary ovarian insufficiency is peripheral and destroys follicles (high FSH/LH, low estrogen). PCOS involves dysregulated pulsatility and hyperandrogenism (high LH, normal FSH, high testosterone). Prolactinomas secrete prolactin which centrally inhibits GnRH (high prolactin, low FSH/LH, low estrogen).

Step-by-Step Solution

Analyze the clinical presentation of the collegiate gymnast with low BMI.

Identify the condition as functional hypothalamic amenorrhea due to chronic energy deficit.

Low body weight and high physical stress suppress hypothalamic GnRH pulsatility, causing hypogonadotropic hypogonadism.

Analyze the presentation of the woman with autoimmune diseases (vitiligo, hypothyroidism) and hypoestrogenic symptoms.

Identify the condition as primary ovarian insufficiency (POI).

Autoimmune destruction of ovarian follicles leads to decreased estrogen production and loss of negative feedback, resulting in elevated FSH and LH.

Analyze the presentation of the woman with obesity, oligomenorrhea, and hirsutism.

Identify the condition as polycystic ovary syndrome (PCOS).

PCOS is marked by hyperandrogenism and altered gonadotropin dynamics (elevated LH, normal FSH) without significant estrogen deficiency.

Analyze the presentation of the woman with headaches, amenorrhea, and galactorrhea.

Identify the condition as a prolactinoma (pituitary adenoma).

Hyperprolactinemia suppresses GnRH, leading to suppressed FSH/LH and decreased estradiol, while the mass effect causes headaches.

Key Concept

Pathophysiology and laboratory profiles of secondary amenorrhea and ovulatory dysfunction

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